Association of Orthodontic Tooth Movement with Leptin Concentration in Gingival Crevicular Fluid.

Objectives: This study aims to evaluate the association of orthodontic tooth movement with the concentration of leptin in gingival crevicular fluid (GCF). Materials and
Methods: In thirty orthodontic patients, the concentration of leptin was assessed at baseline, 1 h, 24 h, 7 days, and 1 month after application of orthodontic force. Distalized tooth movement was evaluated by measuring the difference on dental casts at baseline and 1 month after force application.
Results: Average concentration of leptin in GCF raises from baseline (T0) to 1 h after application of force (T1). There was a significant association of the overall average concentration of leptin with the degree of tooth movement (correlation coefficient = 0.625).
Conclusion: There was a biphasic change in GCF leptin concentration and significant association between rates of tooth movement with GCF leptin concentration. Copyright:

INTRODUCTION

Usually, during orthodontic tooth movement, there will be significant raise in numerous cytokines such as; interleukin 1-beta, interleukin-6, pentraxin-3, B2 microglobulin, tumor necrosis factor ∝, matrix metalloproteinases, and enzymes such as lactate dehydrogenase and alkaline phosphatase.[1] Leptin which is found in the gingival crevicular fluid (GCF) has higher concentrations in subjects with healthy gingival tissues as compared to subjects with periodontal disease. Leptin has a direct role in bone formation by enhancing osteoblast proliferation and differentiation.[1]

This study was done to compare the mean concentration of leptin to the rate of tooth movement.

MATERIALS AND METHODS

Thirty orthodontic patients of both genders with equal sample sizes were included for the present study. This study was conducted in the department of orthodontics and dentofacial orthopedics. Informed consent was obtained from all the participants.

Inclusion criteria were patients with Angle's Class I malocclusion and Class I skeletal base and maxillary crowding more than 5 mm which requires canine distalization following extraction of all first premolars and healthy patients with healthy gingival, periodontium and absence of anomalies. Exclusion criteria were subjects with presence of oral habits and subjects not willing to participate.

Fixed orthodontic alignment was initiated with an initial archwire of 014-inch NiTi. Two weeks after the extraction of all first premolars, distalization of canine was initiated with active lacebacks from canine to the first molar using 0.009” stainless steel wire.

Using strips of filter paper, the GCF sample was collected and the concentration of leptin was assessed at baseline (T0), 1 h after application of force (T1), 24 h later (T2), 7 days after application of force (T3), and 1 month after application of orthodontic force (T4). Baseline acts as control. The concentration of leptin was evaluated by a commercially available enzyme-linked immunosorbent assay.

Casts were made from alginate impression at baseline (T0) and after 1 month after application of force (T4). The rate of tooth movement was calculated as the amount of distal movement of the maxillary canine at the end of 1 month. The amount of canine movement was calculated using Vernier caliper at baseline and after 1 month on cast. The difference between these two values was taken as the rate of tooth movement.

Statistical analysis

The obtained data were tabulated and statistically analyzed using Statistical Package for Social Sciences version 21.0 for Windows (SPSS Inc., Chicago, IL, USA) with t-test, one-way ANOVA with Bonferroni correction. Using Pearson's correlation coefficient, the mean degree of tooth movement was calculated.

RESULTS

Table 1 indicates a comparison of average GCF leptin concentration at various time points. There were significant changes in leptin concentration from T0 to T4. The mean concentration of leptin and degree of tooth movement did not have any statistically considerable gender variation (P > 0.05) [Table 2]. There was a significant association of the overall mean concentration of leptin with the degree of tooth movement (correlation coefficient = 0.625) [Table 3].

Table 1

Comparison of mean gingival crevicular fluid leptin concentration at various time points

Time points (T)	Time points (T)	Significance
0	1	0.001**
	2	0.107
	3	0.000***
	4	0.000***
1	0	0.002 **
	2	0.178
	3	0.000***
	4	0.000***
2	0	0.107
	1	0.178
	3	0.016*
	4	0.060
3	0	0.000***
	1	0.000***
	2	0.014*
	4	0.000***
4	0	0.000***
	1	0.000***
	2	0.060

*Significance at 0.05 level, **Significance at 0.01 level, ***Significance at 0.001 level, test used - ANOVA

Table 2

Gender difference in mean gingival crevicular fluid leptin concentration at various time points and in the rate of tooth movement

Time points	Gender	Number of subjects (n)	Mean GCF leptin concentration (pg/μL)	SD	Significance
T0	Male	15	311.42	97.12	0.712
	Female	15	321.53	75.58
T1	Male	15	412.78	58.38	0.248
	Female	15	376.85	78.86
T2	Male	15	849.69	725.34	0.315
	Female	15	1038.26	1079.82
T3	Male	15	35.24	15.75	0.268
	Female	15	25.18	14.83
T4	Male	15	242.72	114.12	0.922
	Female	15	249.25	125.24
Rate of tooth movement	Male	15	0.78	0.42	0.138
	Female	15	1.12	0.31

n: Number of subjects, GCF: Gingival crevicular fluid, SD: Standard deviation

Table 3

Correlation of gingival crevicular fluid leptin concentration to the rate of tooth movement

Correlation	Degree of tooth movement	Mean
Degree of tooth movement (mm)
Pearson corelation	1	0.625**
Significance (two-tailed)		0.002
N	30	20
Pearson corelation	0.625**	1
Significance (two-tailed)	0.002
N3030	N3030	N3030

**Significant, P<0.01 level. n: Number of subjects

Graph 1 indicates oblique that leptin levels could reach baseline values within a month following a single orthodontic activation.

Graph 1

Mean and standard deviation of gingival crevicular fluid leptin concentration at T0, T1, T2, T3, and T4

DISCUSSION

Since leptin has a role in bone remodeling action, this study was done to evaluate the role of leptin level on the degree of tooth movement.

Dilsiz et al. concluded that the concentration of leptin in GCF is decreased by orthodontic tooth movement, which is contradictory to our results.[1] Srinivasan et al. concluded that there was a positive correlation among tooth movement and GCF leptin concentration.[2] These results are in accordance with our findings. Jain et al. found that leptin may be one of the mediators associated with orthodontic tooth movement.[3]

Jayachandran et al. observed decreased degree of tooth movement in obese individuals and salivary leptin levels.[4] We found a positive correlation between leptin level and tooth movement. Further studies are needed to verify the outcome.

CONCLUSION

It was observed that leptin concentration in GCF is positively associated with the degree of tooth movement.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.